JPH04281626A - Satellite mount repeater - Google Patents

Abstract

PURPOSE:To easily correct the fluctuation of a frequency of a satellite mount repeater and grasping the frequency fluctuation generated in the repeater at a base station. CONSTITUTION:A reference oscillator 19 is provided in a satellite and oscillator outputs 1-8 are distributed to each frequency conversion section. Each frequency conversion section controls the frequency of a local oscillator built in the frequency conversion section so as to be an integral multiple based on a signal of the reference oscillator 19. Thus, the frequency fluctuation of all channels is recognized from a frequency fluctuation of a specific channel. Thus, the frequency of a demodulator input signal is easily subjected to fluctuation correction control and the base station easily control frequencies of all signals without giving load on a mobile body transmitter-receiver.

Description

[0001] The present invention relates to a satellite-mounted repeater that relays communications between satellite communication transmitting and receiving stations within a multi-beam in satellite communication using multi-beams. It is. [0002] Conventionally, as a repeater for the purpose of communication between a base station and a satellite communication transmitting/receiving station, especially a mobile object, using multi-beam satellite communication, the one shown in FIG. 3 has been considered. It is being Here, a base station refers to a base station that connects signals from a mobile object to a terrestrial communication network via the base station, and also connects signals from a terrestrial communication network to a mobile transmitter/receiver station via a base station and a satellite. It also performs functions such as connecting signals from a mobile body to the mobile body via a satellite, a base station, and a satellite. In FIG. 3, signals from a base station to a plurality of mobile transceiver stations existing in each multibeam are received by a satellite antenna 101, collectively amplified and frequency converted by a receiver 103, and then separated. The wave transmitter 104 divides the beam into a plurality of frequency bands corresponding to multi-beams according to the frequency band. Each divided signal is individually amplified and frequency-converted by transmitters 105-1 to 105-m corresponding to the beam, and then amplified by a power amplifier, and transmitted to antennas 102-1 to 102-m.
Each beam is emitted from 102-m. On the other hand, signals from the mobile transmitting/receiving station in each beam to the base station are sent to the antenna 110-1 for each beam.
After receiving at ~110-m, receiver 111-1 in the satellite ~
After being amplified and frequency-converted by 111-m, the signals from each beam are combined by a multiplexer 112, collectively amplified and frequency-converted by a transmitter 113, power amplified, and radiated from an antenna 114 to a base station. be done. Here, each frequency converter 106, 108-1 to 108-m, 115-1
~115-m, 117 are each individually equipped with a local oscillator 107.
, 109-1 to 109-m, 116-1 to 116-m,
118 is built in. In addition, receivers 111-1 to 11
1-m have similar configurations, but in order to avoid complication in the diagram, one of the receivers is shown as 111-i, and the frequency converter 111
-i, the configuration is shown as local oscillator 109-i. The same applies to transmitters 105-1 to 105-m. [0005] The structure of a conventional repeater is as described above. For this reason, for example,
For signal transmission from a base station in beam s to a mobile transceiver station in beam i, the repeater input frequency is Fb
, s, i, the repeater output frequency f, m, s, i for i beam is expressed as follows. fm, s, i =Fb, s, i −F1 +F
2, i, where F1 is the frequency of the local oscillator 107 of the frequency converter 106 of the receiver 103, and F2, i is the frequency of the local oscillator 1 of the frequency converter 108-i of the transmitter 105-i.
09-i frequency. Similarly, for a signal from a mobile transceiver station in beam i to a base station in beam s, if the repeater input frequency is fm, i, s, then the repeater output frequency for the base station is Fb, i, s is expressed as follows. Fb, i, s = fm, i, s −F3, i
+F4 However, F3,i is the frequency of the local oscillator 116-i of the frequency converter 115-i of the receiver 111-i,
F4 is the frequency of the local oscillator 118 of the frequency converter 117 of the transmitter 113. When the output frequency of each of the local oscillators described above changes due to changes in the temperature of the satellite environment, the frequencies of signals received by the mobile transceiver station and the base station change as shown below. Δfm, s, i −ΔFb, s, i =−ΔF
1+ΔF2, iΔFb, i, s −Δfm, i
, s = -ΔF3, i+ΔF4 In the conventional repeater configuration, since each local oscillator is independent, its fluctuations are uncorrelated, and the frequencies generated within the repeater for each signal vary independently. [0008] In mobile communications where the transmission speed is low, countermeasures against frequency fluctuations are essential for stable signal demodulation. For this reason, frequency control becomes important and frequency fluctuation detection is required. For this purpose, when trying to understand the frequency fluctuations of each signal at the base station, it is necessary to monitor all the signals coming from each beam and know their frequencies, which makes it extremely difficult to understand the frequency fluctuations. This method has the disadvantage that it is complicated and the device configuration becomes complicated. Furthermore, regarding signals from the base station to the mobile transceiver station, only the signals for the beam to which the base station belongs can be monitored, but signals for other beams cannot be received, so the signals cannot be monitored. It has the disadvantage that it is impossible to detect frequency fluctuations occurring within the repeater. The present invention has been made to solve these conventional problems, and it calculates the value of the frequency fluctuation occurring within the repeater for signals corresponding to all beams.
The purpose is to provide a means by which the base station can easily understand the information. [0010] According to the present invention, the above problems can be solved and the above objects can be achieved. That is, the present invention can receive a signal from a base station in multi-beam satellite communication where a service area is covered by a plurality of beams and provide communication between the plurality of beams and one base station. There is a function that converts, amplifies, and then sends the signal to the satellite transmitting/receiving station corresponding to each beam, and a function that receives the signal from the satellite transmitting/receiving station within each beam, performs frequency conversion, amplifies, and then transmits the signal to the satellite transmitting/receiving station corresponding to each beam. A repeater mounted on a satellite that has the function of sending signals from a beam to a base station all at once.It is equipped with one reference oscillator, and the repeater This is a satellite-mounted repeater configured such that the actual frequency conversion amount generated within the reference oscillator is an integral multiple of the frequency of the reference oscillator. [0011] According to the present invention, a reference oscillator is built into the satellite, and the frequencies of all local oscillators have a constant frequency relationship with the reference oscillator. Therefore, if the output frequency Fι,i of each local oscillator in the receiving and transmitting frequency converters is controlled to be synchronized to an integral multiple of the frequency Fr of the reference oscillator, Fi becomes as follows. Fι,i=mi×Fr where mi is a positive integer. As a result, the frequency of all oscillators in the repeater becomes an integer multiple of the reference oscillator, so the frequency fluctuation ΔFi occurring in the repeater becomes is an integer of the frequency of the reference oscillator, as shown in the following equation. ΔFi = | ±mi ±ni | ΔFr Therefore, by detecting the frequency fluctuation ΔFs of one signal of a certain beam s from among many signals, ΔFr can be known, and since mi or ni is known, , the signal from the base station to the mobile transceiver station, and the signal from the mobile transceiver station to the base station. [0013] Furthermore, by using a repeater having such characteristics, the base station can grasp the frequency fluctuations and control the base station transmission frequency, thereby correcting the input frequency fluctuations of the mobile receiving station. Alternatively, instead of controlling the frequency fluctuation of the signal from the mobile transmitting station on the mobile transmitting station side, by controlling the frequency of the local oscillator of the receiving frequency converter on the base station side, the received frequency fluctuation can be controlled. It becomes possible to correct. [Embodiment] An embodiment of the present invention is shown in FIG. As shown in the figure, in the present invention, a reference oscillator 19 is provided within the satellite, and the output of this oscillator is distributed to each frequency converter as shown in *1 to *8. In each frequency converter, the frequency of a local oscillator built in the frequency converter is controlled to be an integral multiple of the frequency of the reference oscillator, using the signal of the reference oscillator as a reference. There is a phase-locked oscillator (PLO) as an oscillator having such a function, and when the frequency of a reference signal is input from the outside, the oscillation frequency of the PLO becomes a frequency that is an integral multiple of the reference signal. Other functions are the same as the conventional configuration. That is, in the figure, 1 is a receiving antenna, 14, 2-1 to 2-m are transmitting antennas, and 4 is a receiving antenna.
is a duplexer, 8-1 to 8-m are frequency conversion/amplification sections, 10
-1 to 10-m represent receiving antennas, and 12 represents a multiplexer. In the figure, for example, for a signal from a base station in beam s to a satellite transmitting/receiving station in beam i, if the repeater input frequency is Fb, s, i, then i
The beam repeater output frequency fm, s, i is expressed as: fm, s, i =Fb, s, i
−F1 +F2, i However, F1 is the frequency of the local oscillator 7 of the frequency converter 6 of the receiver 3, and F2,i is the frequency of the local oscillator 9-i of the frequency converter 5-i of the transmitter 5-i for beam i. It is the frequency. F1 is the reference oscillator m1
If F2,i is synchronized to m2,i times the high frequency, the following results. F1 ×m1 ×Fr F2, i=m2, i×Fr Therefore, fm, s, i =Fb, s, i + (m2,
i-m1)Fr, and the amount of frequency conversion (Fm, s, i-Fb, s, i) within the repeater is as follows. fm, s, i −Fb, s, i = (m2,
i-m1)Fr That is, the amount of frequency conversion within the repeater is an integral multiple of the frequency of the reference oscillator. On the other hand, regarding the signal from the satellite transmitting/receiving station in beam i to the base station in beam s, the input signal frequency of the repeater is fm, i, s, and the repeater output frequency for the base station is Fb, i, If s is assumed, it can be similarly expressed as follows. Fb, i, s − fm, i, s = (n1 −
n2, i) Fr However, receiver 11-i for beam i
The frequency of the local oscillator 16-i of the frequency converter 15-i is n2, i×Fr, the frequency converter 1 of the transmitter 13
Let the frequency of the local oscillator 18 of No. 7 be n1×Fr. [0018] As the temperature within the satellite changes, the frequency of the reference oscillator changes. If this variation is ΔFr and the reference frequency of the reference oscillator is Fr0, then Fr=Fr0+ΔFr. Therefore, the frequency variation generated within the repeater of the signal corresponding to beam i is as follows. ΔFbm, s, i=Δ(fm, s, i −
Fb, s, i) = (m2, i-m1)ΔFr
ΔFmb, i, s = Δ(Fb, i, s
−fm, i, s)=(n1 −n2, i)ΔF
r Here, (n1 - n2, i) and (m2, i - m1) are integers and are known, so if we can know ΔFr, we can calculate the frequency fluctuations of all signals within the repeater. It becomes possible to know. Therefore, a base station in beam s transmits a signal fb, s, s using a pilot signal with a known frequency, and the same base station transmits Fb, s, s corresponding to this signal.
A repeater transmission signal with a frequency of ΔF=(Fb, s, s −fb, s,
s ) = (n1 - n2, s ) By detecting ΔFr, ΔFr can be known, and based on this value, the frequency fluctuation ΔF of all signals generated in the repeater
bm, i, j and ΔFmb, i, j can be easily understood. FIG. 2 shows an example of a method for correcting frequency fluctuations in a base station using the present invention. In the figure, 20 is a satellite-mounted repeater of the present invention, 21 is a satellite-mounted receiving antenna, and 22 is a satellite-mounted transmitting antenna. Further, 60-1 to 60-S indicate multi-beams, and each beam includes transmitting/receiving antennas 50-1 to 50-S and mobile station devices 51-1 to 51-S. The base station 30 is a station belonging to beam S shown at 60-S, and represents a microwave-related device among the transmitting and receiving devices. 31 is an input terminal for an intermediate frequency (IF) signal, 32 is a synthesis circuit that combines the input signal and the pilot signal, and then, in the frequency conversion section 33,
The signal is converted to a transmission frequency, amplified by a high-power amplifier 34, and then transmitted from an antenna 35 to a satellite via a duplexer 36. The duplexer 36 is a circuit that separates transmitted and received signals. On the other hand, the signal received by the antenna 35 is separated by a branching filter 36, subjected to low noise amplification and frequency conversion in a frequency conversion section 40, and then passed through a branching filter 42.
The signal is outputted to the output terminal 43 as an intermediate frequency band signal, and then connected to a demodulator. Frequency converters 33 and 40
have local oscillators 37 and 41, respectively. Reference numeral 39 denotes a pilot signal generation circuit for transmitting to the satellite for frequency control, and its output is input to the synthesizer 32 and the frequency comparison/control section 38. The base station 30 can receive signals directed to the beam S from the satellite. The duplexer 42 is
The signal from the 39 pilot signal generation circuits returns to the base station via the satellite and is separated from the base station received signals. The frequency comparison/control unit 38 compares the frequency of the transmitted pilot signal and the received signal returned via the satellite, grasps the frequency fluctuation within the repeater, and controls the local oscillator 37. Send a signal. The local oscillator 37 changes the frequency based on this control signal to control the transmission frequency. On the other hand, after the signal from the mobile station to the base station is received by the antenna 35, it is separated by the demultiplexer 36, and is subjected to low noise amplification and frequency conversion in the frequency conversion section 40. The signal is output to the output terminal 43 as an intermediate frequency band signal, and then connected to a demodulator. The received frequency fluctuates due to the frequency fluctuations described above within the repeater, but the frequency comparison/control unit 38 can grasp the actual frequency fluctuation amount from the frequency fluctuation of the pilot signal. With the control signal of
By changing the frequency of the local oscillator 41, the intermediate frequency signal frequency output to the output terminal 43 can be controlled. As a result, all signals transmitted from the base station 30 are received by the mobile station 51 because the frequency fluctuations occurring in the frequency converter in the satellite 20 can be corrected by the frequency converter 33 in the base station. The frequency of the signal is always controlled to a constant value. On the other hand, the signal from the mobile station 51 is subject to frequency fluctuations at the repeater, but is corrected at the 40 frequency converters within the base station, so that the signal is always controlled to a constant value at the output terminal 43 within the base station. A signal with a different frequency can be obtained. [0025] The frequency of the oscillator in the repeater varies depending on the temperature and the like. In systems using conventional repeaters, the frequency of each local oscillator fluctuates independently, so if you want to maintain the frequency within a certain range, the base station must adjust the frequency fluctuations of each signal for each channel. According to the present invention, a specific channel 1
By detecting the frequency fluctuations of only the waves, it is possible to know the frequency fluctuations of all channels. For this reason,
In systems that require high frequency stability,
The base station grasps the frequency fluctuations of all signals, changes the frequency of the local oscillator of the base earth station transmission frequency conversion section, controls the transmission frequency to the repeater, and converts the frequency of the received signal from the satellite. By changing the frequency of the local oscillator of the station reception frequency converter, it is possible to easily control the frequency of the demodulator input signal to correct variations. Since the present invention has such characteristics, the repeater according to the present invention can be applied to mobile satellite communications where a large number of signals are transmitted simultaneously, the transmission speed is low, and frequency fluctuation countermeasures are important. This has the advantage that the frequencies of all signals can be easily controlled on the base station side without imposing a burden on the mobile transceiver side.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a frequency fluctuation correction method using the present invention.

FIG. 3 is a diagram showing an example of a conventional multi-beam satellite communication repeater.

[Explanation of symbols]

1,10-1~10-m Receiving antenna 2-1
~2-m,14 Transmission antenna 3,11-
1 to 11-m receiver 4, 42
Duplexer 5-1 to 5-m, 13
Transmitter 6, 8-1 to 8-m, 15-1 to 15-
m, 17 frequency conversion/amplification section 7, 9-1 to 9-m, 16-1 to 16-m, 18, 37
, 41 local oscillator 12, 32, 36 multiplexer 19
Reference oscillator 20 Satellite repeater 21 Satellite receiving antenna 22 Satellite transmitting antenna 30 Base station 31 Base station intermediate frequency signal input terminals 33, 40
Frequency converter 34 High output amplifier 35 Base station transmitting/receiving antenna 38 Frequency comparison/control unit 39 Pilot signal generator

Claims (1)

[Claims] Claim 1. In multi-beam satellite communication where a service area is covered by a plurality of beams and provides communication between the plurality of beams and one base station, a signal from the base station is received and frequency converted. The function is to transmit the signal to the satellite transmitting/receiving station corresponding to each of the above beams after amplification, and to receive the signal from the satellite transmitting/receiving station within each of the above beams, perform frequency conversion and amplification, and then send the signal to the satellite transmitting/receiving station corresponding to each beam. A repeater mounted on a satellite that has the function of transmitting signals from the base station all at once to a base station.It is equipped with one reference oscillator and transmits signals within the repeater via the above signal path. 1. A satellite-mounted repeater characterized in that the actual frequency conversion amount generated in the satellite repeater is configured to be an integral multiple of the frequency of the reference oscillator.